kkarpieszuk

Since version 5.6 Advanced Custom Fields plugin hides WordPress native interface to display custom fields on the posts 
edit screen.
If you are plugin developer, advanced WordPress user or you feel much better when you have custom fields at 
a glance, you probably would like to discard this change.
When you activate this tiny plugin, you will see the native custom fields interface again.

Native Custom Fields Meta Box and ACF

Show WordPress native meta box for custom fields when Advanced Custom Fields plugin is active

drewrawitz

Sometimes you might need to provide image guidelines to your clients who are using the Featured Image meta box. This plugin will allow you to specify different notes for each custom post type that supports Post Thumbnails.

Featured Image Notes

This plugin allows you to add notes to your Featured Image meta box for specific post types.

Native Custom Fields Meta Box and ACF vs Featured Image Notes